In recent years, criminals often use smart phones to commit crimes. In order to effectively combat such crimes, mobile phone forensics has become an essential technology. Through mobile phone forensics, public security organization extracts data from mobile phones, analyzes the data and obtains evidence. Extracting mobile phone data is an important part of mobile phone forensics. This paper makes a brief analysis of mobile phone forensics, and takes Android mobile phone as an example to discuss the data storage architecture and extraction method